D4. Advanced splits for advanced trainees
As you Level Up, things change. You need to manage stressors better. Think of each pattern as a different pathogen.
Lots of pathogens in small doses = manageable.
Lots of pathogens in large doses = omgwtfbbq.
Full body training where you hit each pattern with progressive intent can't be sustained forever. Been there, done that.
Beyond the stress, there's also logistics.
Time is finite. As you get stronger, you need to spend more time with each exercise. One or two warm-up sets turns into four or five warm-up sets. If you do three exercises per training session, this adds up.
Attention is finite. Love and effort falls as the training session progresses. If you're a powerlifter that cares equally about the squat and the bench press, which exercise do you do first? When you're a noob, you aren't giving enough of yourself into either exercise, so it's a wash. But when you're stronger, there's a give and take. It might be best to train the bench press and the squat on their own separate days.
Adaptation is finite. I've been saying a lot of progress is going to come from getting strong on the meat and potato exercises. But what happens if you get strong and still aren't happy with how you look? Maybe you need to add a few extra exercises to target specific areas you're looking to build or improve.
The general rule here is this: general before specific. The general full body routine is done and conquered before you specialize. This rule holds across a variety of different domains. You want your kid to play a variety of sports to develop a broad skill set before specializing.